Class Beta


  • public class Beta
    extends Object

    This is a utility class that provides computation methods related to the Beta family of functions.

    Implementation of logBeta(double, double) is based on the algorithms described in

    and implemented in the NSWC Library of Mathematical Functions, available here. This library is "approved for public release", and the Copyright guidance indicates that unless otherwise stated in the code, all FORTRAN functions in this library are license free. Since no such notice appears in the code these functions can safely be ported to Hipparchus.

    • Method Detail

      • regularizedBeta

        public static double regularizedBeta​(double x,
                                             double a,
                                             double b)
        Returns the regularized beta function I(x, a, b).
        Parameters:
        x - Value.
        a - Parameter a.
        b - Parameter b.
        Returns:
        the regularized beta function I(x, a, b).
        Throws:
        MathIllegalStateException - if the algorithm fails to converge.
      • regularizedBeta

        public static double regularizedBeta​(double x,
                                             double a,
                                             double b,
                                             double epsilon)
        Returns the regularized beta function I(x, a, b).
        Parameters:
        x - Value.
        a - Parameter a.
        b - Parameter b.
        epsilon - When the absolute value of the nth item in the series is less than epsilon the approximation ceases to calculate further elements in the series.
        Returns:
        the regularized beta function I(x, a, b)
        Throws:
        MathIllegalStateException - if the algorithm fails to converge.
      • regularizedBeta

        public static double regularizedBeta​(double x,
                                             double a,
                                             double b,
                                             int maxIterations)
        Returns the regularized beta function I(x, a, b).
        Parameters:
        x - the value.
        a - Parameter a.
        b - Parameter b.
        maxIterations - Maximum number of "iterations" to complete.
        Returns:
        the regularized beta function I(x, a, b)
        Throws:
        MathIllegalStateException - if the algorithm fails to converge.
      • regularizedBeta

        public static double regularizedBeta​(double x,
                                             double a,
                                             double b,
                                             double epsilon,
                                             int maxIterations)
        Returns the regularized beta function I(x, a, b). The implementation of this method is based on:
        Parameters:
        x - the value.
        a - Parameter a.
        b - Parameter b.
        epsilon - When the absolute value of the nth item in the series is less than epsilon the approximation ceases to calculate further elements in the series.
        maxIterations - Maximum number of "iterations" to complete.
        Returns:
        the regularized beta function I(x, a, b)
        Throws:
        MathIllegalStateException - if the algorithm fails to converge.
      • logBeta

        public static double logBeta​(double p,
                                     double q)
        Returns the value of log B(p, q) for 0 ≤ x ≤ 1 and p, q > 0. Based on the NSWC Library of Mathematics Subroutines implementation, DBETLN.
        Parameters:
        p - First argument.
        q - Second argument.
        Returns:
        the value of log(Beta(p, q)), NaN if p <= 0 or q <= 0.